My U.S. Pat. No. 4,627,194, issued Dec. 9, 1986 and its related patents disclose a knife sharpener using magnetic quides which are particularly effective in directing and holding the knife against the moving abrasive surface during the sharpening process. Those patents disclose the knife sharpener as having a pre-sharpening section and honing sections. The abrasive element is rotatably driven in the pre-sharpening section and is orbitally driven in the honing sections. The orbital drive is such that the motion of each abrasive element is limited to a velocity of 800 feet per minute and .+-.0.005 inches in a direction perpendicular to the principle plane (plane of the abrasive surface) and has an orbital length per revolution for each abrasive element of less than about one inch. The orbital motion is also disclosed as inparting to each of the abrasive particles a velocity of no greater than 1500 feet per minute and a motion of no greater than 3/8 inches effective diameter.
It is also disclosed that the orbital velocity should be between 15-1500 feet per minute and that the angle at which the knife is inserted into each honing section should differ in one honing sectiion as compared to the other honing section. Further it is disclosed that the abrasive means should comprise diamond particles with generally flat faces.
The knife sharpener has met with great success, particularly for sharpening knives having normal width blades. There is a need for such a sharpener which can effectively sharpen blades which are very narrow, such as penknives, or which are very wide.